It is a common known knowledge to those skilled in the art that encapsulating packet header can be used to differentiate an encapsulating packet in order to allow a network device to treat the packet with high priority or more importance. Referring now to FIG. 2, examples of an IPv4 packet header and a Type of Service field, which is updated to differentiated services (DiffServ) field, are shown. Packet marking technique to identify packets may include manipulation of the Differentiated Services Code Point (DSCP) sub-field of the Internet Protocol (IP) header Type of Service (TOS) field. DiffServ may provide a networking architecture for classification and management of network traffic as well as Quality of Service (QoS) mechanisms. The DiffServ field may be used in a network layer protocol (e.g., IPv4, IPv6 and mobile IPv6) to make per-hop behavior (PHB) decisions about packet classification and traffic conditioning functions, such as metering, marking, shaping and policing. In FIG. 2, the DSCP field is within the Type of Service (ToS) field of the encapsulating packet header. The DSCP field may provide an indication of the abstract parameters of the quality of service desired. These parameters may be used to guide the selection of actual service parameters when transmitting a packet through a particular network. Several networks offer service precedence, which may treat high priority traffic as more important than other traffic (generally by accepting only traffic above certain precedence at time of high load). The standardized DiffServ field of the packet may be marked with a value so that the packet receives a particular forwarding treatment or PHB, at each network node.
At the transmitter network device, it is desirable for packets with higher priority to be transmitted earlier than packets with lower priority.
However, when an aggregated logical network connection is used to transmit and receive encapsulating packets, the encapsulating packets may be received by the receiver not in sequential order. It is known to those skilled in the art that packets decapsulated from the encapsulating packets should be sorted before being transmitted to the designated recipients. It is also known to those skilled in the art that the sorting can be carried out by using a global sequence number and per logical network connection sequence number encapsulated in the encapsulating packets along with the packets. However, sorting packets can result in delay of transmitting packets when the global sequence numbers are not in sequential order at the receiving network device. When the transmissions of packets with higher priority are delayed due to sorting, the impact of such delay is larger than those of packets with lower priority.
When a network device transmits or receives an encapsulating packet, the encapsulating packet may have a packet format of a usual IPv4 header shown in FIG. 2. It is to be noted that in the above description, it is assumed that the IPv4 header shown in FIG. 2 is used. However, the IPv4 header does not necessarily need to be used, and a packet format of another arbitrary protocol, including IPv6 and mobile IPv6, may be used.